because im really shootin slow in semi then, cause it sounds as if im shootin about the same speed in semi as it does in auto

I'm not so sure it's a thing where you can do it by ear, I mean I do notice a difference in sound when I use semi-auto (I found I could do 14BPS in semi), but we are talking rounds per second...that's pretty tough measurements there and I'm not so sure you can just rely on ear.